Electromagnetic liquid contact relay



Oct. 16, 1962 M. A. TABET ELECTROMAGNETIC LIQUID CONTACT RELAY 2Sheets-Sheet 1 Filed March 8. 1960 Oct. 16, 1962 M. A. TABETELECTROMAGNETIC LIQUID CONTACT RELAY 2 Sheets-Sheet 2 Filed March 8,1960 4INVENTOR MICHAEL A. TABET SUPPLY LOAD United States Patent Otice3,059,077 Patented Oct. 16, 1962 3,059,077 ELECTROMAGNETIC LIQUIDCONTACT RELAY Michael A. Tabet, 1336 Ballentina Blvd., Nortoik 12, Va.Filed Mar. 8, 1960, Ser. No. 13,641 3 Claims. (Cl. 200-112) The presentinvention relates to circuit making and breaking devices of the typewherein an armature is shifted from one operative position to anotherposition in response to a relatively small change in the flux to whichthe armature is subjected providing a sensitive relay and the inventionmore specifically pertains to means enclosing the armature and providingseparate mercury pools through which a circuit is completed in oneposition of the relay.

Various types of switches are known wherein a load circuit is completedfrom one terminal to another by mercury which bridges electrodes carriedby the container for the mercury. In one type of relay the level of theliquid is altered by displacing the 4mercury by means of a plungerresponding to an electromagnetic iield but a high energy level isrequired to actuate such a relay. Other liquid contact switches areactuated by tilting an envelope containing mercury to shift the liquidto a contact making or breaking position. The known types of liquidcontact switches or relays all require relatively high energy levels foroperation and are thus not adaptable to circuit conditions wherein therelay must respond to small current values and a narrow range ofuctuations in the current flowing in the circuit supplying the operatingcoil of the relay.

It is accordingly an object of the present invention to provide a relayof the liquid Contact type with the elements thereof so constructed andarranged that the switch is accurately responsive to small currentvalues in the range of a quarter ampere and less and which isconsistently responsive to predetermined changes in current valuesflowing in the operating coil.

Another object of the invention is to provide a relay of the liquidcontact type which includes enclosure means coniining mercury in onepool into which an electrode carried by the armature is adapted toextend with another electrode carried 4by the armature adapted to extendinto a second pool of mercury coniined in another area or charnber ofthe enclosure means so that a circuit is established from one mercurypool to the other when the armature is in one position whereby the loadcircuit through the -relay is interrupted when the armature is actuatedby the eld developed by the operating coil without shifting or`displacing the mercury.

A more specific object of the invention is to provide an electromaticactuated relay wherein an insulating barrier in association with otherportions of a sealed container maintains mercury into two separate poolsand an armature provided within the container carries electrodes whichextend into the separate pools of mercury when the operating coil isdeenergized so that a circuit is completed from one pool to the otherand a relay wherein a relatively low energy level is required to shiftthe armature and withdraw the electrodes `from one or both of themercury pools.

Other objects and features of the invention will be appreciated andbecome apparent to those skilled in the circuit making and breaking art-as the present disclosure proceeds and upon consideration of thefollowing Adetailed description taken in conjunction with theaccompanying drawings wherein several embodiments of the invention-arefdisclosed In the drawings:

FIG. l is a side elevational view of a relay exhibiting the invention.

FIG. 2 is a sectional View taken on the line 2-2 of FIG. 1 on anenlarged scale and showing the switch in a closed position.

FIG. 3 is a similar view showing the open position.

FIG. 4 is a perspective View of the armature on an enlarged scale.

FIG. 5 is a transverse section taken on the line 5-5 of FIG. 3.

PEG. 6 is an elevational View of the sealed container for the armatureand the mercury pools.

FIG. 7 is a sectional view on an enlarged scale showing a modifiedarmature and insulating barrier.

FIG. 8 is a similar View taken at a right angle to FIG. 7 showing thearmature in the raised position.

FIG. 9 is an enlarged perspective view of the armature and theelectrodes carried thereby employed in the embodiment shown in FIGS. 7and 8.

FIG. l0 is a plan View of the insulating barrier incorporated in theembodiment shown in FIGS. 7 and 8.

FIG. ll is a diagrammatic view of portions of the relay showing one typeof circuit connections.

FIG. 12 isa fragmentary sectional view showing -a shading coil on theiixed core and taken on the line 12-12 of FIG. 2.

IThe invention is directed to a relay wherein a load circuit through therelay is completed by electrodes or conductive elements carried Kby thearmature which extend into separate and electrically isloated pools ofmercury. The electrodes or conductive elements and the armature `are sodesigned and constructed as to -have a small mass yand because noappreciable quantity of mercury is displaced the energy required toshift the armature in response to an electromagnetic field is of a lowvalue. It is for these purposes that the armature is formed principallyas a hollow cylinder which extends into the open axis of an operatingcoil and the annular wall of the hollow cylinder occupies -a positionclose to the inner turns of the coil whereby the air gap between thecoil and the effective portion of the armature is at a minimum. Theshape and arrangement of the insulating barrier in association withother portions of the sealed container and which maintain the mercury inVdistinct pools forms another feature of the invention.

" projection 12 which in cooperation with a nut 14 (FIG.

l) serves as one terminal of the relay. The disc-shaped bottom wall 11and the projection 12 are formed of a metal having good electricalconductive properties. A frusto-conical shaped barrier 1S is arrangedwithin the container 10 and the base end thereof is seated and supportedon the bottom wall 11. The barrier 15 is formed of insulating materialof any suitable type and may be formed of a ceramic material which isbonded to an upturned peripheral flange 16 carried by the bottom wall byan annular joint 17. The upright wall structure for the container 10 isformed of metal having good electrical conducting characteristics andthis element may take the form of a metal tube 18. A second terminal 19(FIG. l) for the relay is carried by the peripheral wall of the tube 1S.The frusto-conical shaped barrier 15 includes an upstanding annularilange 21 at the base end and this iiange surrounds the lower portion ofthe tube 18. When the insulating barrier 15 is formed of ceramicmaterial an annular bond 22 sea'ls the perimeter of the tube 18 withrespect to the llange 21.

The upper end of the tube 18 is closed and this closure means includes aplate 23 of annular shape which may be formed integral with an invertedcup-shaped member 24. The annular plate 23 and the cup-shaped member Z4are desirably formed of a ceramic material or any suitable materialhaving low magnetic permeability characteristics. The perimeter of theannular plate 23 is jointed to the upper end of the tube 18 by means ofan annular bond 26. The inverted cup-shaped member 24 is provided foraccommodating an armature 28 of relatively small mass. The armature 28is best shown in FIG. 4 and it includes a cylindrical shaped or tubularportion 31 which is open at its upper end 32 and open at its llower end33. The external diameter of the tubular portion 31 is such as to titwithin the inverted cupshaped member 24 of the container 10 with aminimum of clearance but suiiicient to provide for free axial movementsof the armature.

The tubular member 31 of the armature carries two circumferentiallyspaced legs 34 and 36 which extend below the lower end 33 of the tubularportion 31. The legs 33 and 34 carry a transversely disposed arm 37which is formed of metal having good electrical conductive properties.An electrode 38 depends from one end of the arm 37 and a similarelectrode 39 depends from the other end of the arm 37. The electrodes 38and 39 diverge outwardly in proceeding downwardly and are of such crosssection as to carry load currents. The armature 28 and the parts carriedthereby is arranged within the container prior to the closing thereof sothat when the container is sealed the armature will be encased withinthe container. The armature may be added in the manufacturing process atany suitable stage prior to closure of the container.

The frusto-conical barrier at the apex end thereof is provided with anaperture 41 with its axis aligned with the axis of the invertedcup-shaped member 24. A passage 4Z extends through the threadedprojection 12 and air may be removed from the container itl through thispassage and an inert gas may be added through the passage 42. A limitedquantity of mercury or any electrically conductive liquid is added tothe container through the passage 42 which may be closed by suitablemeans such as a plug 43. While the mercury is added to the container 1()through the passage 42 it is free to move through the aperture 41 and itis possible that a major portion of the limited quantity of mercury willbe accommodated within the chamber beyond the frusto-conical barrier 15.When the container is erected to a vertical position some of the mercurypasses downwardly through the aperture 41 and this movement of theliquid continues until the level of the liquid exteriorly of thefrusto-conical barrier 15 is no longer above the level of the upper endof thefrustoconical barrier in the vicinity of the aperture 41. Thelimited quantity of mercury is thereby separated into two distinctpools. The mercury above and exteriorly of the inclined portion of thebarrier 15 arranges itself in an annular pool 44. The annular pool ofmercury is in contact with the tube 1S but is insulated from the bottomwall 11 of the container by the base portion of the truste-conicalbarrier 15. The mercury which is moved downwardly through the aperture41 forms a mercury pool 45. The mercury pool 45 is in electrical circuitrelationship with the bottom Wall 11 but is not in electrical conductiverelationship with the tube 18. In the degenerized condition of the relaydisclosed the electrodes 38 and 39 extend into the annular mercury pool44. The circumferential spacing of the electrodes 38 and 39 maintainselectrical circuit relationship of at least one of these electrodes withthe mercury pool 44 even when the relay assembly is not maintained withits axis in a true vertical position.

The armature 28 carries an electrode 46 which is in electricalconductive relationship with the arm 37. The electrode 46 extends belowthe arm 37 and in the deenergized condition of the relay the electrode46 extends through the aperture 41 and into the mercury pool 45 which issupported on the bottom wall of the container and confined within thefrusto-conical barrier 15. The

4 mercury pool 45 is in electrical conductive relationship to the bottomwall 11 and the projection 12 which serves as a terminal for the relay.

An operating coil 50 for the relay is carried by a spool type frameformed of insulating material. The internal diameter of a sleeve 52ofthe coil Aframe is of such dimensions as to fit snugly about theexternal diameter of the inverted cup-shaped member 24. A lower annularflange 53 of coil frame engages and lies along the upper face of theannular plate 23 of the container 1t). The peripheral wall of thecup-shaped member 24 and the thickness of the sleeve 52 are as small aspossible so as to reduce to a minimum the air gap between the armature28 and the coil 50. A stationary core 56 is mounted in the upper end ofthe sleeve 52 and this core may if desired be provided with a shadingcoil 55 as shown in FIGS. 2 and l2 particularly when the relay is to beoperated by alternating current. The core 56 is adjustable axially ofthe coil 50 and any suitable means may be provided for effecting suchadjustment. In the embodiment illustrated a rod 57 is carried by thecore 56 in threaded engagement with a bracket 5S supported in anysuitable manner such as by the upper annular flange 54 of the coilframe. Rotation of the threaded rod 57 adjusts the axial position of thecore 56 to vary the pick-up point of the armature 28. The threaded rod57 may be maintained in an adjusted position by means of a lock nut 59.

In handling the assembled relay such :as during shipment the mercury inthe annular pool 45 lwithin the frusto-iconical carrier 15 may passthrough the aperture 41 so that substantially all of the mercury may beaI- ranged in the container 10 externally yof the barrier 15. When therelay is erected in a vertical position as shown the mercury may tend tobridge the aperture 41 because of the surface tension of the mercury andany gas that is trapped in the lower chamber of the container within thebarrier 15 may be suliicient to prevent Ia suiiicient quantity ofmercury to pass downwardly through the aperture 42. In order to vent thelower chamber later-ally disposed holes `61 are provided in theelectrode 46 which is of tubular construction. Any gas that is trappedunder pressure below the frusto-conical barrier 15 may enter the tubularelectrode 46 through the holes `61 and pass into a hollow stem 62 whichforms an extension of the electrode 46. The hollow stem 462 extendsthrough the arm 37 and into the tubular portion 31 of the larmature. Theupper portion of the hollow stem 62 is provided with laterally disposedholes `64 so that gas pressures of the two chambers in the container 1t)may become equal. The lower end of the electrode 46 is closed asindicated at 66 and the upper end `of the stern 62 is closed asindicated at 67. The lateral disposition of the holes 61 and 64 avoidthe possibility of free particles closing these apertures. When therelay is in the deenergized condition `the lower end of the tubularelectrode 46 engages the bottom wall 11 and limits downward movement ofthe armature. The holes 61 are so located that they remain above thenormal level of the mercury in the pool 45.

The relay has -utility for the purpose of completing and interrupting aload circuit wherein the current is relatively high and the controlcurrent relatively low. The relay has been found suitable to controlstreet lighting equipment wherein such a lamp is energized in responseto the absence of natural light falling on a photoelectric device suchas indicated at 68 in FIG. l1. The photoelectric device 68 in theabsence of a predeterminedlevel of light has such `high resistance thatthe circuit supplying current `to the coil 50 is such that the uxdelveloped thereby is insuiiicient to lift the armature 28. The loadcircuit `from one side of the supply extends through the terminal 19,the sleeve 18 of the container 1t), the mercury pool 44, the electrode38, the arm 37 'and the electrode 46 and the mercury pool 45 to thebottom wall 11 and terminal 12 so that the load circuit is closed. Whensuiicient light falls on the photoelecbric unit 68 the resistancethereof is reduced and the current owing in the coil 50 increases andthe change in the current -owing in the coil 50 may be `gradual and ofIa small value and usually less than one-fourth of an am pere. Thearmature 28 and the electrodes carried thereby is of such small mass andthe periphery tubular portion v31 of the armature is -so closely locatedto the turns of the operating coil 50 that the armature is lifted at -agiven value of current llowing in the coil 50. As the armature 28 israised the electrodes '38 and 39 are removed frorn contact with theannular mercury pool 44. The load circuit is accordingly interrupted andthe la-mp is no longer energized. The upper end of the tubular portion31 of the armature engages the closed end 69 of the inverted `cup shapedmember 24 to limit upward movement of the armature.

A modication is shown in FIGS. 7 to 10 wherein the stem 62 carried bythe armature in thev first embodiment is omitted and a vent passage 71is provided through the wall of la. modified frusto-conical barrier 15a.In this embodiment a projection 7-2 of insulating material such as asuitable ceramic extends `above the level of the mercury forming theannular pool 44. The projection 72 may be *formed integral with thefrusta-conical barrier 15a and the passage 71 terminates :above Ithelevel of the limited quantity of mercury. In lthe event the entirequantity should be arranged exteriorly of the barrier 15a. The lower endof the passage 71 is in communication with the chamber below thefrustoconical barrier 15a so that the pressures within the two chambersmay lbe equalized to facilitate the return of mercury through theaperture 41.

While the invention has been described with reference to specicstructural characteristics and with regard to various types of materialit will be appreciated that changes may be made in these structuralelements as well as the general organization including the materialsforming various parts of the Irelay. Such modifications and othersincluding the types yof circuits that may be ernployed in associationwith the relay may be made without departing from the spirit and scopeof the invention as set forth in the app-ended claims.

What I claim and desire to secure by Letters Patent is:

1. In an electromagnetically actuated relay, a sealed container, lafrusto-conical barrier of electrical insulating material within saidcontainer, :a quantity of mercury within said container below saidfrusto-conical barrier, a quantity of mercury within said containerexteriorly of said l)Srusto-conical barrier, 'an armature within saidcontainer, `an electrode carried by said armature Iadapted to extendinto the mercury located exterior-ly of said ifrustoconical barrier,said frusto-conical barrier having Ian :aperture in the apex portionthereof, a second electrode carried by the armature in electricalconductive relationship with the iirst electrode adapted to dependthrough said aperture int-o the mercury below the frusto-conicalbarrier, a coil `for shifting said armature, tubular means extendingabove said frusto-conical barrier having yan opening therein providing apassage from an `area adjacent and under the apex portion of saidbarrier to a zone above said frusto-conical barrier for venting gasestrapped below the frusto-conical barrier.

2. In an electromagnetically actuated relay according to claim l whereinsaid tubular means -is carried by said armature.

3. In an electromagnetically :actuated relay according to clai-In 1wherein the tubular means is carried by the frusto-conical barrier.

References Cited in the rile of this patent UNITED STATES PATENTS536,811 Lemp Apr. 2, 1895 773,119 AChristmas Oct. 25, 1904 1,604,495Steinmayer Oct. 26, 1926 2,072,210 Klinkhamer Mar. 2, 1937

